LIFE CYCLE ASSESSMENT OF THE ENVIRONMENTAL IMPACT OF BIOSURFACTANT PRODUCTION FROM OIL WASTE BY A DICULTURE OF AZOTOBACTER VINELANDII AND PSEUDOMONAS SP.
During the bioprocess of the biosurfactant production (by the consortium), the volume of CO2 evolved was 28.23 ± 5.08 cm3, which is equivalent to 0.056 ± 0.01g CO2 per 100 ml of broth. In terms of gCO2/1000Kg biosurfactant, this gave a value of 4545 ± 817.93g CO2 in this bioprocess. Following from above, the life cycle impact assessment (LCIA) of biosurfactant production by this consortium, based on global warming potential (GWP) was 0.046 tonnes/1000Kg biosurfactant. Other impact values calculated for acidification and eutrophication potentials were 0.008 tonnes / 1000 Kg and 0.0014 tonnes/1000Kg of biosurfactant. These values were considered insufficient in terms of environmental pollution when compared with the regular methods of surfactants production. In this work also, the consortium of Pseudomonas sp/Azotobacter vinelandii produced 1.22 ± 0.04 mg biosurfactant per 100ml of cell – free broth. However, the individual organisms (Pseudomonas sp. and Azotobacter vinelandii) produced 1.03 ± 0.02 and 0.08 ± 0.001 mg of biosurfactants per 100 ml cell – free broth respectively. The microbial growth kinetics during the production of the biosurfactant by the consortium gave a specific maximum growth (µmax) of 1.306 ± 0.201 hr-1), a saturation constant (Ks) of 0.017 ± 0.007 mg/l, an Inhibition constant (Ki) of 121.83 ± 21.18 mg/land a Death constant (Kd) of 0.017 ± 0.006 mg/l. These values when compared with those of individual organisms shows that using a consortium for the bioprocess is more sustainable.